I. Technical Field
The present invention relates to a radiation therapy planning apparatus and a radiation therapy planning method, and more particularly to a radiation therapy planning apparatus and a radiation therapy planning method which are used for creating a therapeutic plan of radiation therapy for treating a patient by irradiating the affected part with radiation.
II. Description of the Related Art
A radiation treatment is known in the art which treats a patient by irradiating an affected part (a tumor) with therapeutic radiation. An example of the therapeutic radiation is an X-ray. Known radiation therapies include irradiation of a wider range than the affected part in view of the magnitude of the movement of the affected part, the gated irradiation, the moving body tracking irradiation, and the intensity modulated radiation therapy (IMRT). The gated irradiation is a method for irradiating the therapeutic radiation and stopping the irradiation on the basis of the movement of the observed patient. Such gated irradiation suffers from a drawback of an increased treatment time, since the irradiation of the radiation is performed only during a specified phase of breathing, for example, which puts a strain on the patient and necessitates an improvement in the efficiency of the medical treatment. The tracking irradiation is a method for observing the position of the affected part and irradiating the position with therapeutic radiation. The IMRT is a radiation method which involves varying the amount of the radiation with which each portion of the patient is irradiated through combining a plurality of beams, to thereby carry out a radiation therapy suitable for the shape of the tumor. The radiation therapy is desired to have a high therapeutic effect and desired to be evaluated more adequately.
A 4D-CT which allows obtaining a three-dimensional image for each breathing phase is known in the art. A four-dimensional radiation therapy planning apparatus for carrying out an estimation of dose distribution to a moving target by using such three-dimensional images is developed, and a radiation therapy system which is able to change the direction of X-ray irradiation in real time and to track the target is known in the art. Moreover, a technique is known in the art which allows checking positions of internal organs in real time by combining not only the X-ray imaging but also the MRI apparatus with the radiation therapy apparatus. Furthermore, an adaptive therapy is known in the art in which the therapy is implemented while being modified on the basis of the movement of these organs, a change of body contour, and each therapy result.
A four-dimensional therapy planning apparatus is known in the art which carries out the planning by using tomography images of the 4D-CT according to a plurality of phases of the breathing. The four-dimensional therapy planning apparatus first obtains a plurality of tomography images corresponding to the respective phases of the breathing (for example, eight phases) by using the 4D-CT. The four-dimensional therapy planning apparatus then constructs a correspondence relationship between the shape of organ deforming along with the breathing and the breathing phases. When an inputted therapy plan is carried out, the four-dimensional therapy planning apparatus calculates the radiation dose with which the organ extracted from the tomography image of each phase is irradiated. The four-dimensional therapy planning apparatus calculates the dose with which the organ is irradiated by summing the doses in the respective phases on the basis of the correspondence relationship. Generally, the radiation exposure from 4D-CT acquisition is large, and the temporal resolution of 4D-CT images is low. It is desired that the dose of the X-ray with which the patient is irradiated is reduced and that the dose with which the patient is irradiated in the radiation therapy is calculated more accurately.
Disclosed in Japanese Patent Application Publication No. H08-089589 is a display method used for radiation therapy planning which can create a therapy plan in view of a plurality of conditions of a subject moving in the irradiation area. The display method used for the radiation therapy planning is characterized by including steps of: reading a series of CT images obtained in each of a plurality of different conditions to set an irradiation area, an irradiation-free area and a radiation therapy parameter; creating projection shapes for respective different conditions by projecting the irradiation area and the irradiation-free area on the irradiation field on the basis of the same geometric conditions as those of the irradiation; superimposing the projection shapes of the irradiation areas created in each of a plurality of different conditions at each of respective irradiation angles; creating an irradiation field shape at each of the respective irradiation angles on the basis of the irradiation area superimposed at each of the respective irradiation angles and the set radiation therapy parameter; and superimposing the superimposed irradiation area and the created irradiation field shape at each of the respective irradiation angles and displaying them.
Disclosed in Japanese Patent Application Publication No. 2001-327514 is a radiation therapy planning apparatus which can carry out the setting accurately in view of the position and shape of the affected part which change in accordance with the breathing and heartbeats of a subject to achieve more precise and accurate radiation therapy. The radiation therapy planning apparatus, which creates a plan of the radiation therapy on the basis of an image obtained by irradiating an X-ray to the subject, is characterized by including: image generation means adapted to generate a plurality of images according to difference of phase data of the subject; input means adapted to set and input to the images a target shape to an objective portion existing on the image; and image display means adapted to superimpose and display a plurality of images and the target shapes according to difference of said phase data and said target shape.
Radiation treatment is known in the art which treats a patient by irradiating an affected part (a tumor) with therapeutic radiation. An example of the therapeutic radiation is an X-ray. Known radiation therapies include irradiation of a wider range than the affected part in view of the magnitude of the movement of the affected part, the gated irradiation, the moving body tracking irradiation, and the intensity modulated radiation therapy (IMRT). The gated irradiation is a method for irradiating the therapeutic radiation and stopping the irradiation on the basis of the movement of the observed patient. Such gated irradiation suffers from a drawback of an increased treatment time, since the irradiation of the radiation is performed only during a specified phase of breathing, for example, which puts a strain on the patient and necessitates an improvement in the efficiency of the medical treatment. The tracking irradiation is a method for observing the position of the affected part and irradiating the position with therapeutic radiation. The IMRT is a radiation method which involves varying the amount of the radiation with which each portion of the patient is irradiated through combining a plurality of beams, to thereby carry out a radiation therapy suitable for the shape of the tumor. The radiation therapy is desired to have a high therapeutic effect and desired to be evaluated more adequately.
Disclosed in Japanese Patent Application Publication No. 2006-021046A is a radiation therapy apparatus which achieves real time monitoring of the state of the therapeutic field even during therapeutic irradiation. The radiation therapy apparatus includes: an O-shaped gantry; an irradiation head for irradiating a therapeutic radiation to a therapeutic field of a subject, the irradiation head being movably provided for said O-shaped gantry; an X-ray source for irradiating a diagnostic X-ray to said therapeutic field of said subject, the X-ray source being movably provided for the O-shaped gantry; and sensor arrays for detecting a transmission X-ray of said diagnostic X-ray transmitting through said subject to output diagnostic image data, the sensor arrays being movably provided for said O-shaped gantry, wherein the sensor arrays are disposed at symmetrical positions across the irradiation head and move on said O-shaped gantry in synchronization with movement of the irradiation head, and the X-ray source moves in synchronization with movement of said sensor arrays.
Disclosed in Japanese Patent Application Publication No. 2007-236760A is a radiation therapy apparatus control device that irradiates a portion of a moving subject with radiation, more accurately. The radiation therapy apparatus control device controls a radiation therapy apparatus including: a therapeutic radiation irradiation device for irradiating a portion of a subject with therapeutic radiation; a movement detection device for detecting movement of said subject; and a drive device for moving said therapeutic radiation irradiation device with respect to said subject; the radiation therapy apparatus control device includes: an affected part position database for correlate movement aggregation with position aggregation; a movement collection part for collecting the movement from the movement detection device; and an irradiation position control part for moving the therapeutic radiation irradiation device by using said drive device so that the position corresponding to said movement of said position aggregation can be irradiated with the therapeutic radiation.
Disclosed in Japanese Translation of PCT Application No, 2008-514352 is a reliable and efficient method for dynamically tracking a moving target. The method that dynamically tracks one or more targets in an anatomical region including one or more reference structures and gives a therapeutic radiation said target during movement of said anatomical region, includes steps of: detecting in real time an existence position of said target with respect to said reference structure in said moving anatomical region; and generating a radiation dose distribution to prescribe a desired dose of said therapeutic radiation to be given in real time said target in the moving anatomical region, wherein said radiation dose distribution takes into account deformation of said anatomical region in said movement.